1. Field of the Invention
The present invention relates to a solar cell, more particularly relating to a backsheet of a solar cell.
2. Description of the Prior Art
The backsheet of a solar cell can protect the solar cell from water, moisture, and heat-distortion and provide the functions of insulating and bottom lining. The defects of the backsheet of the solar cell will results in a short lifetime of the solar cell. The micro-crystalline (C—Si) solar cell usually comprises the backsheet of the Tedlar/polyethylene terephthalate/Tedlar (TPT) or Tedlar/polyethylene terephthalate/ethylene-vinyl acetate (TPE) structure. The thin-film solar cell usually comprises the backsheet of Tedlar/aluminium/polyethylene terephthalate (TAP) or Tedlar/aluminium/polyethylene terephthalate/ethylene-vinyl acetate (TAPE) structure.
Please refer to FIG. 1, which represents a schematic view of a conventional backsheet of a solar cell. The backsheet 1 of a solar cell comprises, sequentially from bottom to top, a bottom plastic layer 20, a first insulating layer 22, a conductive water-proof layer 24, and a weather-resistant layer 28.
However, the voltage-resistant ability of the weather-resistant layer of the conventional backsheet is usually one-third of that of the normal insulating layer. Such configuration tends to result in the defect of arc fail if a pinhole occurred in the solar cell. The defect of pinhole can be prevented by increasing the thickness of the weather-resistant layer. However, the cost of the manufacturing of the backsheet will be therefore increased as well.
Please refer to FIG. 2, which represents a schematic view of another conventional backsheet of a solar cell. The backsheet 2 of a solar cell comprises, sequentially from bottom to top, a bottom plastic layer 20, a first insulating layer 22, a conductive water-proof layer 24, and a second insulating layer 26.
The second insulating layer 26 is known to comprise a better voltage-resistant ability and a less expense than the normal weather-resistant layer. And the defect of the arc fail can be prevented by increasing the thickness of the second insulating layer up to 50 μm (micrometer). However, the second insulating layer is not resistant to UV light and the defect of pinhole cannot be prevented if the second insulating layer is of single-layered configuration.